1. Field of the Invention
The present invention relates to an organic electroluminescent (EL) device, and more particularly, to an organic EL device that resists external moisture and oxygen permeation.
2. Description of the Background
Generally, moisture and oxygen deteriorate organic EL devices. Consequently, an encapsulation member may be required for an organic EL device to prevent moisture and oxygen permeation.
Conventional encapsulation methods include forming a cap-shaped metal can or glass that provides a recess for accommodating a powdered absorbent for absorbing water, and forming a film-type double-sided tape for adhesion (U.S. Pat. No. 5,771,562 and Japanese Laid-open Publication No. hei 03-261091). U.S. Pat. No. 6,268,695 discloses a method of forming a protective layer by alternately depositing an organic substance and an inorganic substance over an organic EL unit.
However, placing a desiccant powder in a recess may be complex and expensive. Additionally, forming the recess may increase a substrate's overall thickness, and a non-transparent encapsulating substrate prevents fabrication, of front emitting and dual (i.e. front/rear) emitting devices. Additionally, since etched glass used as the encapsulation member may be brittle, external impact may easily damage it. When passivation is achieved using films, moisture permeation may not be substantially prevented. Further, the film-type encapsulation member may have poor durability and low reliability because it may have limited capability to prevent moisture infiltration, and it may be easily torn during fabrication or use. Therefore, passivation using a film may not be suitable for mass production. The method of forming an organic/inorganic multi-layered protective layer may require alternately depositing organic thin films and inorganic thin films, and a glass or metal cap may be needed for encapsulation.